This joint research has been conducted to develop methods for predicting rainfall runoff, sediment yield and runoff, river changes and coastal erosion, as well as to develop scientific basis for water and sediment hazards mitigation in Indonesia. The principal results are swninarized as follows :A long- and short-term rainfall-nuioif model was tested to evaluate the water balance and rainfhll a runoff disehaige in the Sutami reservoir basin. The results show this model can reproduce daily rainfall-runoff using the variable infiltration capacity model, even in tropical drainage basins.Remote sensing images and geographic information systems (GIS) were used for establishing a distributed hydrological model for flood and sediment runoff The model applied to the Putili river, a tributary of the Brantas, reproduced the sediment yield during the seven years following the 1990 eruption of Mt. Kehid and estimated the effective infiltration depth that contributes to sediment yield.Based on samp
… Moreled bed materials at about thirty points in the basin, soil property and particle size were investigated. One- and two- dimensional bed variation models were applied to the middle reach of the Brantas. The l-D model investigated the effect of channel width on bed variation and the effect of suspended load, and revealed that the rapid change in channel width causes greater river bed variation. The 2-D model showed that the stream bifurcation took place in broadening reaches and suspended load accentuated the coarsening of sediment at the inner bank of curved sections of the river.Coastal monitoring and numerical prediction have been conducted in Pangandaran coast (South Java), facing the Indian Ocean, were river short-cut works are under construction.One-year simulation of tide- and wind-driven circulation in Java Sea, wiuich is influenced by the west- and east- monsoons, was carried out using a three-dimensional hydrodynamic model incorporating the influence of waves. A third-generation ocean wave prediction model, WAM, was employed to calculate the wave fields and the wave-dependent sea surface and bottom drag coefficients.Six-hourly wind fields at 10 in above the sea surface ware given by ECMLWF's global climate reanalysis data as a representative wind. The trajectory of munnerical tracers was simulated to understand transport of materials at both the sea surface and bottom. A 3-D beach change prediction model which consists of a bore type breaking wave model, 3-D near-shore circulation model and sediment transport model, has been developed in this project. Its verification has been continued on coasts both in Japan and Indonesia. Less